There are generally only two reasons for something like this, both of which are covered in this FAQ:
http://rocketgeek.com/plugins/wp-members/docs/faqs/#passwords
It’s never “for no reason at all.” It’s likely that you changed something you didn’t realize would affect the login process.
I have not made any changes at all to the plug-in or made any other changes to the back end settings. Could this be a compatibility issue with the latest version of Word Press? I am running WP version 4.7.2. The problem began just a few days ago.
Sorry to repost, but as I really need to have this plug-in working, are there any suggestions as to how it can be fixed? Thanks.
Did you review the FAQ link that I posted (especially item #2)?
Yes, I did. That was the first thing I checked. No changes were made. All was working well and then it wasn’t. Do you have any other things that can be checked? As I said, I do need it working as soon as possible.
Contact me through the support site and include a link to your site so I can take a look (and ideally, include a list of active plugins as well).
http://rocketgeek.com/contact/
Just to come back and make sure this post has a resolution for anyone coming to it later, the issue was in fact what was outlined in the FAQ that I posted in the initial response.